Adafruit USB Wired Mouse - Two Buttons plus Wheel
This is a mouse. A nice, simple mouse. No bells or whistles. Just a mouse.
But that doesn't mean it's not the best simple mouse! We compared a few and liked this one the most. It's optical for good resolution and precision, two buttons for use with any kind of OS, and has a USB connector that's pretty sturdy. The track wheel has a good spin and click action. The right and left click also make a nice satisfactory sound which we always enjoy. Its small but not too small.
Comes in a nice glossy black as seen in the beautiful photos above (we think it's just about the most beautiful looking mouse we've ever seen.) It's also big enough to fit your hand comfortably.
This'll work well with Raspberry Pi but also any other kind of computer as its a standard HID mouse!